Another line of work exploit reinforcement learning to optimise the model based on the evaluation metrics [1]}, [2]}, [3]}. These models take the action of predict the next word, given the states of visual, textual, and context vectors, to obtain the reward measured by caption evaluation scores.
Other innovate methods focus on domain transfer [4]}, [5]}, [6]}, object hallucinations and gender bias in generated captions [7]}, [8]}, topic modelling [9]}, Model efficiency [10]}, [11]}, [12]}, etc.
